The invention relates to maskless lithography, and relates in particular to maskless lithography using arrays of focusing elements.
U.S. Pat. No. 5,900,637 discloses a system for maskless lithography that involves the focusing of incident energy from a single energy source onto a substrate as focused beamlets. The arrangement includes micro-mechanical devices with actuatable shutters that turn the focused beams on and off in response to commands from a control computer. To write a pattern, the substrate is scanned under the array, while the individual beams are turned on and off as needed by means of the micro-mechanical shutters, one associated with each zone plate. These shutters are disclosed to be located either between the zone plate array and the substrate, or between the zone plate array and the source of radiation. The '637 patent also discloses a lithography system that includes an array of micro-mechanical, deflectable glancing-angle mirrors that may be used to turn individual focused beams on and off.
Such lithography systems, however, require that zone plate arrays be very precise and uniform without significant variation. In certain applications the use of individually created zones on zone plates may not be appropriate.
There remains a need therefore, for an improved method of forming arrays of zone plates or other diffractive elements for a maskless lithography system.